Centimeter Polarimetry of the R Coronae Australis Region

Abstract

Circularly polarized 3.5 cm continuum emission was detected toward three radio sources in the R CrA region using the Very Large Array. The Class I protostar IRS 5b persistently showed polarized radio emission with a constant helicity over 8 yr, which suggests that its magnetosphere has a stable configuration. There is a good correlation between the Stokes I and Stokes V fluxes, and the fractional polarization is about 0.17. During active phases the fractional polarization is a weakly decreasing function of Stokes I flux, which suggests that IRS 5b is phenomenologically similar to other types of flare stars such as RS CVn binaries. The variability timescale of the polarized flux is about a month, and the magnetosphere of IRS 5b must be very large in size. The Class I protostar IRS 7A was detected once in circularly polarized radio emission, even though IRS 7A drives a thermal radio jet. This detection implies that the radio emission from the magnetosphere of a young protostar can escape the absorption by the partially ionized wind at least once in a while. The properties of IRS 7A and IRS 5b suggests that Class I protostars have organized peristellar magnetic fields of a few kilogauss and that the detectability of magnetospheric emission may depend on the evolutionary status of protostar. Also reported is the detection of circularly polarized radio emission toward the variable radio source B5.

To appear in the Astrophysical Journal

References in corpus (8)

• Radio Observations of a Large Sample of Late-M, L, and T Dwarfs: The Distribution of Magentic Field Strengths
• Simultaneous X-ray, radio, near-infrared, and optical monitoring of Young Stellar Objects in the Coronet cluster
• The Detection and Characterization of cm Radio Continuum Emission from the Low-mass Protostar L1014-IRS
• High Spatial Resolution Observations of Two Young Protostars in the R Corona Australis Region
• Centimeter Imaging of the R Coronae Australis Region
• VLA multifrequency observations of RS CVn binaries
• Radio continuum imaging of the R CrA star-forming region with the ATCA
• Resolving a Class I Protostar Binary System with Chandra

Cited by in corpus (8)

• Time Monitoring of Radio Jets and Magnetospheres in the Nearby Young Stellar Cluster R Coronae Australis
• The Young Binary DQ Tau: A Hunt For X-ray Emission From Colliding Magnetospheres
• Possible Signatures of Magnetospheric Accretion onto Young Giant Planets
• VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme UV- and X-ray-driven disk photo-evaporation -- A pathfinder for Square Kilometre Array studies
• Hunting for millimeter flares from magnetic reconnection in pre-main sequence spectroscopic binaries
• JVLA Observations of Young Brown Dwarfs
• A Very Long Baseline Interferometry Detection of the Class I Protostar IRS 5 in Corona Australis
• Radio Variability Survey of Very Low Luminosity Protostars